1. Field of the Invention
The present invention relates to a communication system mounted on a vehicle, the system having multiple communication devices which are selectively used.
2. Description of Related Art
Various communication devices in an Intelligent Transport System (ITS) field, such as devices corresponding to a Vehicle Information and Communication System (VICS) and an Electronic Toll Collection (ETC), are going to be mounted on an automotive vehicle in addition to a conventional automotive cellular phone. A communication system using satellites for efficiently managing an operation schedule of commercial vehicles is already in the market. In such a system, communication via satellites is utilized in addition to surface communication by a conventional telephone. Also, a Dedicated Short Range Communication (DSRC) system that is to be used in communication between a vehicle and roadside devices is now being developed. Under these circumstances, various communication devices corresponding to respective systems will be used in a vehicle in the near future.
When multiple communication devices are mounted on a vehicle, it is very important to select an appropriate device for actual use, because a position of the vehicle always changes and all the devices are not necessarily usable at a given vehicle position. Therefore, it is highly desirable to provide a system to help a user to select the appropriate communication device at a given situation. Moreover, such selection has to be done in consideration of various factors, such as urgency of communication, amount of data to be transmitted and charges for the communication.
The present invention has been made to solve the potential problems mentioned above, and an object of the present invention is to provide a system which helps a user to select appropriate communication devices from among multiple devices mounted on a vehicle in accordance with varying vehicle positions. Another object of the present invention is to provide a system in which communication is performed under desired conditions including communication time and charges. Yet another object of the present invention is, when plural devices are selected, to determine an order of use of the selected devices.
A communication system that includes multiple communication devices is mounted on a vehicle. The communication devices respectively correspond to various communication systems, such as a DSRC, a middle range, a stationary satellite, a cellular phone and a low orbit satellite communication system. The on-board communication system also includes a controller to select one or plural communication devices which are most appropriate in a given situation from among the multiple communication devices.
Ever-changing vehicle positions are detected by a vehicle position detector, and information showing a present vehicle position is fed to the controller. The controller selects one or more communication devices that are usable at the detected present vehicle position, considering field intensity at that position. The controller also specifies one or more communication devices that are available at a communication receiving end. Both the usable devices and the available devices are memorized in memories. One or more communication devices to be actually used are selected from among the devices that are usable at the present vehicle position as well as available at the receiving end.
Preferably, the on-board system further includes a device for setting communication conditions according to user""s preference. Conditions, such as a condition under which a communication time has priority and a condition under which communication charges have priority, may be set by a user. When there are plural pieces of data to be transmitted, those data may be classified into a few classes according to their urgency, so that the urgent data are transmitted first. When there are plural devices that are selected to be used, a user may select one device from those for actual use, or may set an order of use. Alternatively, the order of use may be determined by the controller based on the conditions set by the user.
According to the present invention, a communication device that can be appropriately used at the present vehicle position is efficiently selected from among multiple communication devices mounted on a vehicle. Also, the communication between a vehicle and arbitrary locations including other vehicles can be efficiently performed, taking into consideration urgency and user""s preferred conditions.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiment described below with reference to the following drawings.